In conventional, as shown in FIG. 21, there has been known a fuel cell in which an electrolyte membrane 51, catalyst electrodes 52 and 53, gas diffusion layers 54 and 55, separators 56 and 57 and gaskets 58 and 59 are assembled in an illustrated manner. In these constituting parts, the electrolyte membrane 51 constitutes a membrane electrode complex (also called as a reaction electrode portion or an MEA) together with the catalyst electrodes 52 and 53 arranged on both surfaces thereof, and the membrane electrode complex 60 constitutes a UEA 61 together with the gas diffusion layers 54 and 55 arranged on both surfaces thereof. Further, as shown in FIG. 22, a gas communication groove 62 is provided in the separators 56 and 57 in a predetermined plan layout, and a spacer 63 is arranged in this portion in place of the gasket 58 or 59. With respect to the other portions, the gaskets 58 and 59 fixed to the separators 56 and 57 clamp the electrolyte membrane 51 between them so as to secure a sealing property.
However, in accordance with this prior art, since the gaskets 58 and 59 fixed to the separators 56 and 57 clamp the electrolyte membrane 51 between them, whereby the sealing property is secured as mentioned above, there is a disadvantage that the electrolyte membrane 51 tends to be broken near the gaskets 58 and 59. The electrolyte membrane 51 tends to be affected by dry and wet due to operation and stop of the cell, and there is a risk that the electrolyte membrane 51 is broken in a short time period due to a great stress caused by compression and expansion of the membrane. Further, in accordance with the prior art mentioned above, since the spacer 63 having a high rigidity must be independently arranged in the portion of the gas communication groove 62, an assembling step for the cell is complex, and thus a contact state with the electrolyte membrane 51 is different from the other portions, so that the structure is made such that the electrolyte membrane 51 tends to be broken.
Further, in accordance with the prior art mentioned above, since the constituting parts are sequentially assembled at a time of assembling the cell, there is a disadvantage that the assembling step is complex in view of this point. That is, as described above, the fuel cell has the separator constituted by the carbon plate or the like, the membrane electrode complex for reacting the gas, the gas diffusion layer made of a carbon fiber or the like for promoting a gas diffusion, and the gasket made of a rubber elastic material or the like for sealing the gas and a refrigerant, as the main constituting parts, however, since these constituting parts have been conventionally assembled sequentially at a time of assembling the fuel cell, a lot of labor and time are required for this assembly. On the other hand, in recent years, there has been invented an integral product of the separator and the gasket in which the gasket is integrally formed directly on the carbon plate (refer to Japanese Unexamined Patent Publication No. 2000-133288), however, it is impossible to avoid the structure in which the spacer 63 having a high rigidity is independently arranged in the portion of the gas communication groove 62, so that the cell assembling step becomes complex, and it is hard to carry out an automation for the purpose of reducing the manufacturing cost, in a stacking step of alternately stacking the separator and the UEA.
The gas diffusion layer is made of a sintered body, a woven fabric or a non-woven fabric of a fiber-like material such as a carbon fiber, a metal fiber, an inorganic fiber or the like, and is a porous body having a continuous gas permeability since a gas permeability is required. Accordingly, a rigidity and a strength are lower than a dense structure body, the gas diffusion layer tends to be collapsed due to an excessive pressurization so as to be permanently deformed, and a handling property is not good in view of an assembling work. Accordingly, shapes of the gaskets are not uniformed due to a breakage, a collapse or a deformation of the gas diffusion layer caused by pressurizing for positioning or integrating at a time of forming the gasket or assembling with the membrane electrode complex, the separator or the like after forming the gasket, so that there is fear that a surface pressure required for sealing with respect to an opposing surface to the gasket is short or excessive. Further, since the gas diffusion layer has the porous structure, there is fear that a gas is leaked in a layer direction of the gas diffusion layer.
The present invention is made by taking the above matter into consideration, and an object of the present invention is to provide a fuel cell and a manufacturing method of the same which can effectively prevent an electrolyte membrane from being broken, can make an assembling step for the fuel cell easy, and can achieve an excellent sealing property.
In this case, the present invention can be also applied to a fuel cell which directly use a liquid fuel such as a methanol or the like (a direct methanol fuel cell), in addition to a fuel cell which uses a gas fuel such as a hydrogen or the like.